The present invention relates to a vacuum cleaner. More particularly, the present invention relates to a vacuum cleaner which detects when a dust bag is full with sucked dust.
In the past, an arrangement of a vacuum cleaner is popularly employed that an air intake and an air outlet are provided whereby a vacuum cleaner body, a dust bag and a fan motor are provided at predetermined positions at an interior of the vacuum cleaner body. Specifically, the fan motor is disposed with its outer periphery surrounded by an airtight packing.
When the vacuum cleaner having the above arrangement is employed, a suction force (negative pressure) is generated by the fan motor, air including dust is sucked by the suction force through a suction nozzle, a suction pipe and the air intake, and the dust is collected by the dust bag while the air penetrates the air bag and is exhausted through the air outlet to an exterior of the vacuum cleaner body. Therefore, a quantity of dust collected by the dust bag increases by performing a cleaning operation intermittently or continuously for a long time period, and the dust bag approaches a full condition with collected dust.
When the dust bag is filled with sucked dust, the dust bag is blocked and the air penetration ability of the dust bag is lost. Therefore, the suction force from the fan motor is not transmitted to the air intake so that a condition is realized that air is scarcely suctioned (and cleaning is scarcely performed). Consequently, the collected dust within the dust bag should be removed from the dust bag when such a condition is realized.
A mechanism (i.e., a dust quantity display mechanism) for detecting a condition where the dust bag is filled with collected dust is provided in a conventional vacuum cleaner. As shown in FIGS. 8 and 9, the mechanism includes a casing 41 having a rectangular parallelepiped shape, a cylindrical shape or the like and a communicating pipe 42 provided at a wall of the casing 41, which wall is at one end in a longitudinal direction of the casing 41. The communicating pipe 42 communicates an interior of the casing 41 and a space (the space rear of the dust bag) between the vacuum cleaner body and the dust bag, as is illustrated in FIG. 8. A display body 44 is housed within the casing 41 in a slidable manner and a spring 45 is provided for urging the display body 44 in a direction away from the communicating pipe 42. Further, a transparent window 43 is provided at a predetermined position of a wall which is parallel to the moving direction of the display body 44. The transparent window 43 is used to visually recognize a position of the display body 44. A collected dust quantity display (for example, showing empty, medium and full) 46 for indicating a collected dust quantity is provided at a predetermined position of the casing 41 adjacent to the window 43, as is illustrated in FIG. 9.
When this arrangement is employed, and when a quantity of dust collected within the dust bag is nearly zero, a large quantity of air is suctioned through the air intake by the fan motor which is rotated at high speed, so that a negative pressure within the space rear of the dust bag becomes extremely small. Therefore, the display body 44 is moved by the spring 45 to display that a quantity of dust collected within the dust bag is nearly zero (refer to the display body 44 and the collected dust quantity display 46 in FIG. 9).
On the contrary, when the dust bag is filled with suctioned dust, a quantity of suctioned air through the air intake is almost zero even when the fan motor rotates at extremely high speed, so that a negative pressure within the space rear of the dust bag becomes extremely great. Therefore, the display body 44 is moved against the force of the spring 45 to display that the dust bag is filled with suctioned dust.
Further, when the quantity of dust collected within the dust bag is an intermediate quantity, the negative pressure within the space rear of the dust bag varies in correspondence to the quantity of collected dust. Therefore, the display body 44 is moved in correspondence to the amount of negative pressure and the force of the spring 45 so that a quantity of dust collected within the dust bag is displayed.
The dust quantity display mechanism having the above arrangement is a mechanism which is quite different from the cleaning function which is the essential function of a vacuum cleaner. Therefore, providing the dust quantity display mechanism is performed by adding an extra mechanism to the vacuum cleaner. Consequently, a disadvantage arises that a manufacturing cost of a vacuum cleaner is increased.
Further, as is apparent from the above description, the dust quantity display mechanism must be disposed in the vacuum cleaner body. A disadvantage arises in that visually recognizing the dust quantity display mechanism becomes inconvenient and a forced condition for a cleaning operator. More particularly, a cleaning operator actually performing a cleaning operation performs a cleaning operation while looking at an operating section and the like which is provided at the suction nozzle or the suction pipe. And, during the cleaning operation, the vacuum cleaner body moves in a pulled manner by the suction pipe. Therefore, when the dust quantity display mechanism is to be visually recognized, an operator must turn back to look at the vacuum cleaner body and into the transparent window 43 having an extremely small size in comparison to a size of the vacuum cleaner body. Consequently, visually recognizing the dust quantity display mechanism is inconvenient and a forced condition to a cleaning operator.